如何通过注释使Groovy脚本中的私有字段可用

Question

For instance I have a class:

public class Model1 {
  @Bind private int val;
}

and I have an annotation

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)

public @interface Bind {


}

I would like to pass an object of Model1 class to the Groovy script but I will not have the val available in that script. Can I make it avaiable by @Bind annotation?

Answer 1

If you do not have accessors for your private field, the only way to achieve what you want is to use reflection.

First, get all fields of your model, :

Model1.getClass().getDeclaredFields()

It will return list of declared fields. Then, iterate over list and check if field is annotated with Bind:

field.getDeclaredAnnotation(Bind.class)

this method will return null if field is not annotated with 'Bind' annotation.

And finally, make private field accessible:

field.setAccessible(true);

Now do watever you need with field